1. Field of the Invention
The present invention relates to safety devices for miners, and particularly to a dust collection and air filtration device for use with a roof drill, also known as a roof bolter, used in the mining industry.
2. DESCRIPTION OF RELATED ART
It has been found that the rock in a mine roof may be adequately supported by bolts placed in the roof instead of posts or columns. The procedure used in placing bolts in the mine roof involves drilling a hole for the bolt in the roof with a device known as a mine drill. The drill is mobile, usually being mounted on a truck, and has a hydraulically operated roof support, often counterbalanced by a floor support so that the roof support is not borne by the truck during drilling operations. The truck bears at least one drill, and frequently two drills, including a chuck, a motor (either electric or hydraulic), a drill steel, and a rock cutting drill bit, collectively referred to as a "drill pot" in this application. After the hole is drilled in the roof, an expansion bolt is placed in the hole with a resin, wedging the rock in the roof.
A problem which arises during the drilling operation is that a great deal of dust and rock cuttings are generated as the drill bores into the mine roof. The dust poses a hazard, both generating the potential for explosion, and also as a health hazard to mine workers. Consequently, roof drills are generally equipped with some sort of apparatus for collecting the dust. Since the roof drill is often operated in a long tunnel or cavern, the air supply is limited, and therefore the dust collector also includes a filtration device in order to remove the dust from the air and to recirculate the air.
U.S. Pat. No. 2,590,958, issued Apr. 1, 1952 to R. H. Goodrich, describes a dust collector for a stoper type pneumatic roof drill. The device has two semicylindrical portions which are hinged together to form a cone shaped funnel about the drill steel. A side discharge tube is connected to the funnel, the discharge tube having a nozzle casing defining a venturi having a jet connected to a fluid source, which creates a vacuum which sucks the dust into the funnel and through the discharge tube.
U.S. Pat. Nos. 2,829,867 and 2,829,908, issued Apr. 8, 1958 to R. E. Brochetti and to Brochetti, et al. respectively, describe a dust collecting head for a roof drill and means for supporting the head. The dust collector includes a cylindrical housing with a sleeve through which the drill is inserted, and a discharge nozzle connected to a suction source entering the side of the housing and penetrating to the air gap between the sleeve and drill. The housing includes a conical, suction cup type disk adapted for attachment to the roof of the mine.
U.S. Pat. No. 2,832,567, issued Apr. 29, 1958 to Fletcher, et al., discloses a mobile roof drill. The roof drill includes a collar around the drill steel serving as a guide, with a funnel-like collector around the upper end of the collar and a side collector hose connected to a vacuum source.
U.S. Pat. No. 4,081,041, issued Mar. 28, 1978 to Perri, et al., teaches a dust collecting head for a roof drilling machine having two symmetrical halves of a funnel shaped member pivotally attached to arms which close around the drill rod to form a cup. Two conduits are attached to the narrow portion of the funnel tangentially and 180.degree. apart, the conduits being attached to a vacuum source and creating a swirling effect to suction off the dust.
U.S. Pat. No. 4,099,937, issued Jul. 11, 1978 to Ufken, et al., shows a multi-stage filter for the dust collecting apparatus of a roof drill. The dust is collected from the drill hole by suction applied to a hollow drill rod surrounding the drill bit. The dust laden air is processed through dust collection chambers including a cyclone separator, a tubular separator, and a paper filter before being exhausted to the atmosphere.
Other dust collecting devices for rock drills are shown in U.S. Pat. No. 1,057,568, issued Apr. 1, 1913 to Mayer, et al. (tubular body clamped to the stem of the drill); U.S. Pat. No. 1,972,846, issued Sep. 4, 1934 to G. S. Kelley (deflector having the shape of the frustum of a cone mounted about drill steel, and a conduit attached to a sidewall of the deflector which is connected to a blower motor for withdrawing the dust); U.S. Pat. No. 3,924,696, issued Dec. 9, 1975 to Horlin, et al. (for a drill which injects air through the drill bit to blow the cuttings out of the hole, a shell mounted around the drill stem which injects air downward to slow the upward rush of air from the hole, and a side discharge tube connected to a vacuum); and United Kingdom Patent No. 266,630, published Mar. 3, 1927 (drill passing through a T-connector with rubber cups, the side arm being connected to a second T-connector).
Other dust collectors for drills generally include U.S. Pat. No. 4,205,728, issued Jun. 3, 1980 to Gloor, et al. (suction attachment around drill bit with side discharge tube having a nozzle creating venturi effect); U.S. Pat. No. 4,444,280, issued Apr. 24, 1984 to D. F. Howeth (for a drill which drills into the ground, a collector including a duct angling upward and having two rigid sections connected by a flexible hose); U.S. Pat. No. 4, 921,375, issued May 1, 1990 to G. Famulari (a bell shaped bellows attached to a drill coaxial with the bit); U.S. Pat. No. 5,090,499, issued Feb. 25, 1992 to G. L. Cuneo (for a portable hand drill, a suction head with a drill bit extending transversely through the suction head); and U.S. Pat. No. 5,605,421, issued Feb. 25, 1997 to P. Hodgson (drill bit extending through dust extractor attached to vacuum cleaner).
A device for removing gas and dust from mines is shown in U.S. Pat. No. 1,578,814, issued Mar. 30, 1926 to A. D's Ascenzo, the device including a motor on a truck driving two fans, one of the fans having a flexible hose directed towards the roof of the mine for withdrawing gas to a compressor and flask where it is sealed by a valve for disposal, and the other fan being connected to a flexible hose directed to the floor of a mine for collecting dust which is collected in a bag for disposal.
It will be observed that prior dust collecting devices for roof drills employ either a vacuum applied to a hollow drill bit for suctioning cuttings from the drill hole, or a cup or funnel shaped collector with a vacuum for suctioning the dust vertically downward from the drill hole parallel to the sides of the drill steel. Such devices are generally effective for withdrawing relatively large cuttings having significant mass. However, there are still problems associated with collecting finer dust particles generated by roof drills.
With several of these devices, the collection head cannot be maintained in constant contact with the roof of the mine. The air currents surrounding the entrance of the drill hole are complex, and finer particles may be forced laterally before entering the vacuum zone of the collecting head. Hence, miners may still be required to wear rebreathing apparatus to avoid collecting fine particles of quartz or coal dust in their lungs, which may result in silicosis, pneumoconiosis and other respiratory diseases.
The air filtration device for use with a roof drill solves this problem by providing a dust collection head attached to a vacuum source, the dust collection head being fixedly positioned at the roof of the mine lateral to the entrance of the drill hole. The device is used in conjunction with a dust collection device vertically below the drill hole so that dust is removed from the air adjacent the drill hole.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.